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O: Oberflächenphysik
O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)
O 14.73: Poster
Montag, 27. März 2006, 18:00–21:00, P2
Diffusion of interstitial carbon atom in graphite studied by Van der Waals-corrected density functional theory — •Yuchen Ma1,2, A.S. Foster2, A.V. Krasheninnikov2, and R.M. Nieminen2 — 1School of Engineering and Science, International University Bremen, P.O. Box 750 561, D-28725 Bremen, Germany — 2Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, Helsinki 02015, Finland
Present first-principle methods based on density functional theory (DFT) fail to describe the VdW interaction in graphite correctly. An empirical long-range dispersion term is incorporated into the DFT-based VASP code within the GGA in order to study the diffusion of interstitial carbon atom in graphite.
On a graphene sheet, the ground state of carbon adatom has been calculated to form a bridge-like structure by forming two bonds with two atoms in the graphene. By VASP code, a metastable state is found for the adatom. In this metastable state, the adatom pushes one atom in the graphitic network out of the graphene plane and these two atoms form a symmetric structure with respect to the graphene plane.
Calculations by both the VASP code and the VdW-corrected VASP code show that in AB-stacking graphite single interstitial carbon atom prefers to form four bonds with adjacent two graphene layers, i.e. two bonds with each layer. The diffusion along the c-axis is through the metastable state discussed above and the diffusion energy along this path is about 1.0 eV. Our calculations show that the diffusion of single interstitial in graphite is isotropic.